Tuesday, April 24, 2012

Courtesy Streets

by Michael Sarazen

Courtesy streets are
two-way streets where vehicles have to make room for each other to pass.
Parking can exist on one or both sides and pavement markings are rare. By not having enough room for two cars
to pass, when there is an encounter in which two vehicles are approaching from
opposite directions, one vehicle will pull off to the side of the road and
allow the other vehicle to pass, hence the courtesy aspect of the street.

A typical curb-to-curb
cross section of a courtesy street with parallel parking on both sides would be
26 to 30 feet. With 7 foot wide parking on both sides, this would mean a single
12 to 16 foot travel lane for both directions of travel. This width would easily
allow a single vehicle on the road, but as it would allow for 6 to 8 feet per
vehicle during an encounter, it would require one vehicle to stop and move to
the right, either against the curb or into available parking while the passing
vehicle is allowed to slowly pass around the stopped vehicle.

In terms of safety,
courtesy streets act as a form of traffic calming, slowing traffic along a road
by having these encounters. An encounter greatly reduces the speed of passing
vehicles and discourages most cut-through traffic.

Encounter
between two passenger vehicles from perspective of car pulled off to the sideQuincy Street approaching Mass Ave, Arlington MAGoogle Maps Location

People are only willing
to drive slowly for a limited amount of time and through a couple encounters. For
this reason, courtesy streets are only used for roads intended to have low
volumes. In order to keep volumes low, courtesy streets are often short, with larger
streets intersecting them every few blocks and running parallel to them. This
encourages drivers to use the larger streets as opposed to the smaller, more
residential streets. This helps to make neighborhoods quieter, safer, and more
enjoyable.